dillon1000/react

Check for passive effects on the root fiber (#19488)

The root fiber doesn't have a parent from which we can read the
`subtreeTag`, so we need to check its `effectTag` directly.

The root fiber previously did not have any pending passive effects,
but it does now that deleted fibers are cleaned up in the passive phase.

This allows us to remove a `schedulePassiveEffectCallback` call from the
synchronous unmount path.

Co-authored-by: Brian Vaughn <[email protected]>